If you're having problems with the video not looking right (messed up colors),
go into the properties of their the game's executable, or the shortcut to it,
go to the "Compatibility Tab", and check the box "Run in 256 Colors".
I tried this with my copy of Warcraft 2 Battle.net Edition, and it also
I think my colors are fine in XP SP3. Well, fine may not be the right word...they are sometimes ugly, but I think its the original color!
BTW, I saw an article on Kotaku about all the mods that have already been made with the SCII game editor...including Asteroids...uh oh, SCII is starting to tempt me again. Somebody hold me back!
Another thought based on the previous issue of whether the d/l will continue to be online or not. I was looking at Blizzard and Battle.net web sites and its real clear that they have discontinued support for the previous product shortly after releasing the sequel. For example, Diablo went away after Diablo II and WCII Battle.net went away after WCIII. I think it is VERY likely they will stop supporting (which likely means taking the download down) SCI a short period of time (2-3 months at most) after releasing SCII.
Obviously no hard evidence for this, but looking at the past pattern and how Activision/Blizzard does business, its quite likely.